RESUMEN
The objective of this study was the evaluation of the genetic diversity found in HBV circulating among Venezuelan Amerindians and the general population in Colombia. Phylogenetic analysis of the S region in 194 isolates showed that genotype F is highly predominant in Colombia and Venezuela. This might be related to the genetic background of the population. F3 is the main subgenotype which circulates in both countries. Phylogenetic analysis of 61 complete genome sequences of HBV American genotypes confirms the presence of two genotypes F and H, and 4 F subgenotypes. In Venezuela, subgenotypes F1, F2, and F3 circulate in East and West Amerindians, while only F3 was found among South Amerindians. Japreira community derived from Yucpa Amerindians around 150 years ago. However, several Japreira HBV sequences were forming a clade that can be classified as subgenotype 2b, differing from Yucpa sequences that belong mainly to subgenotype F3. The apparent absence of correlation between the phylogenetic groupings of HBV isolates with the ethnical origin in aboriginal populations might be suggesting a recent origin of HBV American subgenotypes, or a genetic drift effect.
Asunto(s)
Variación Genética , Genoma Viral , Virus de la Hepatitis B/genética , Hepatitis B/virología , Colombia/epidemiología , Etnicidad , Genotipo , Hepatitis B/epidemiología , Virus de la Hepatitis B/química , Virus de la Hepatitis B/clasificación , Humanos , Epidemiología Molecular , Datos de Secuencia Molecular , Filogenia , Grupos de Población , Venezuela/epidemiologíaRESUMEN
Tranfusion-transmitted virus (TTV), a single-stranded circular DNA virus that chronically infects humans and other animals, displays a high degree of genetic diversity and was originally thought to be associated with hepatitis. The prevalences of TTV infection among different populations of humans and non-human primates from Venezuela have now been evaluated, using serum samples and three different detection tests. All three tests were PCR-based, one involving a hemi-nested PCR and primers based on the N22 open-reading-frame-1 region (N22-PCR), another employing 55 cycles with primers from the more conserved untranslated region (UTR-PCR), and the other using a hemi-nested PCR with primers from the same region (HUTR-PCR). The overall prevalences of human infection appeared much higher with the HUTR-PCR (52%) than with the N22-PCR (13%) or the UTR-PCR (5%). When the products amplified by N22-PCR from 28 human isolates of TTV were sequenced, only two genotypes of the virus were detected. The non-human sera tested came from primates kept in a zoo in north-western Venezuela. TTV DNA was detected, by HUTR-PCR, in both of the chimpanzee sera tested but not in any of the sera from the 11 New-World primates or the other 12 Old-World primates that were investigated. The results, particularly those of the HUTR-PCR, indicate that TTV infection is common in Venezuela, especially in populations, such as many Amerindian groups, who live under poor sanitary conditions. Although TTV infection may be relatively rare among non-human primates from the New World, this will have to be investigated further, using many more samples collected throughout the Americas.
Asunto(s)
Infecciones por Circoviridae/epidemiología , Enfermedades de los Primates/epidemiología , Torque teno virus/genética , Adulto , Anciano , Animales , Infecciones por Circoviridae/etnología , ADN Viral/sangre , Femenino , Genotipo , Humanos , Indígenas Sudamericanos , Masculino , Persona de Mediana Edad , Filogenia , Reacción en Cadena de la Polimerasa/métodos , Prevalencia , Salud Rural , Venezuela/epidemiologíaRESUMEN
The genotypes of hepatitis B (HBV) and delta (HDV) viruses circulating among Venezuelan Amerindian populations, where these viruses are endemic, were determined by sequencing of PCR amplified products from HBsAg positive sera. HDV genotype I (n = 7, 6 from West Amerindians), and III (n = 5, 4 from South Amerindians), were found. Only one HDV genotype I isolate was associated with HBV genotype D, 4 HDV genotype I and 2 HDV genotype III infected individuals were co-infected with HBV genotype F. The failure to detect the South American HDV genotype III in West Amerindians might be related to the outbreak of fulminant hepatitis with high mortality rate occurred between 1979 and 1982, probably affecting more the Amerindians infected with HDV genotype III. These results suggest the circulation of HDV genotype I among Amerindians, probably introduced through European immigrations, and that this HDV genotype is able to replicate in association with HBV genotype F.
Asunto(s)
Biomarcadores/análisis , ADN Viral/análisis , Anticuerpos Antihepatitis/análisis , Virus de la Hepatitis B/genética , Hepatitis D Crónica/complicaciones , Hepatitis D/complicaciones , Hepatitis D/genética , Virus de la Hepatitis Delta/genética , Indígenas Sudamericanos/genética , ARN Viral/análisis , Secuencia de Aminoácidos , Secuencia de Bases , Biomarcadores/sangre , ADN Viral/sangre , Genotipo , Anticuerpos Antihepatitis/sangre , Anticuerpos Antihepatitis/inmunología , Hepatitis B/sangre , Hepatitis B/virología , Antígenos de Superficie de la Hepatitis B/análisis , Antígenos de Superficie de la Hepatitis B/sangre , Virus de la Hepatitis B/aislamiento & purificación , Hepatitis D/sangre , Hepatitis D/epidemiología , Hepatitis D/virología , Hepatitis D Crónica/sangre , Hepatitis D Crónica/epidemiología , Hepatitis D Crónica/virología , Virus de la Hepatitis Delta/aislamiento & purificación , Humanos , Indígenas Sudamericanos/clasificación , Filogenia , Reacción en Cadena de la Polimerasa , ARN Viral/sangre , Alineación de Secuencia , Venezuela/epidemiologíaRESUMEN
Information on infection with hepatitis C virus (HCV) in South America is scarce. The seroprevalences of antibodies to HCV among urban, rural and Amerindian populations from Venezuela, and the genotypes of the HCV isolates recovered, were therefore determined. A total of 2592 sera were tested with an immuno-assay which was developed in-house and based on synthetic peptides. Each reactive sample was then re-tested, using other enzyme immuno-assays and a reverse-transcription, nested PCR, and any sample confirmed positive (in any test) was considered HCV-positive. Genotypes were determined by analysis of RFLP. Overall, 39 (1.5%) of the samples were found HCV positive. The results of the immuno-assays indicated that the seroprevalence of HCV markers among the Amerindians investigated (23/1082, or 2.1%) was significantly higher than that among the other subjects (16/1510, or 1.1%; P = 0.02). No such difference was observed in the numbers of subjects confirmed positive by PCR, however (6/1082 v. 10/1510), and some of the anti-HCV reactivity observed among Amerindians may have been the result of cross-reactivity with parasitic infections. The relative low prevalence of active HCV infection (16/2582, or 0.6%) and the HCV genotypes observed (mainly genotype 1) are in agreement with the results of previous studies indicating that HCV is not autochthonous to South America. However, it is clear that the virus may now be found even in isolated Amerindian populations. The in-house, synthetic-peptide-based immuno-assay seems to be a valuable tool for epidemiological studies.
Asunto(s)
Hepatitis C Crónica/epidemiología , Tamizaje Masivo/métodos , Juego de Reactivos para Diagnóstico , Adolescente , Adulto , Femenino , Genotipo , Hepacivirus/genética , Hepacivirus/aislamiento & purificación , Hepatitis C Crónica/inmunología , Humanos , Técnicas para Inmunoenzimas , Masculino , Persona de Mediana Edad , Polimorfismo de Longitud del Fragmento de Restricción , Embarazo , Prevalencia , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Salud Rural/estadística & datos numéricos , Sensibilidad y Especificidad , Estudios Seroepidemiológicos , Salud Urbana/estadística & datos numéricos , Venezuela/epidemiologíaRESUMEN
Anti-hepatitis B core antigen (HBcAg)-positive hepatitis B surface antigen (HBsAg)-negative plasma samples from blood donors were tested by nested PCR. DNA positivity was more significantly associated with high levels of anti-HBcAg than with low levels of anti-HBsAg antibodies. Analysis of a dilution of anti-HBcAg antibodies might result in a more rational exclusion of anti-HBcAg-positive HBsAg-negative samples, reducing the number of donations discarded and enabling more countries to incorporate anti-HBcAg testing.
Asunto(s)
Antígenos del Núcleo de la Hepatitis B/inmunología , Antígenos de Superficie de la Hepatitis B/inmunología , Virus de la Hepatitis B/genética , Hepatitis B/diagnóstico , Anticuerpos Antivirales/análisis , Donantes de Sangre , ADN Viral/análisis , Hepatitis B/inmunología , Virus de la Hepatitis B/inmunología , Humanos , Reacción en Cadena de la Polimerasa , VenezuelaRESUMEN
Hepatitis C virus (HCV) genotypes were determined in hemodialysis patients with a high prevalence and incidence of infection. A change of HCV genotype was observed in 6/14 follow-up samples analyzed 13 and 21 months later. The appearance and disappearance of HCV genotypes may be due to either genotype-specific intermittent viremic status or viral interference.
Asunto(s)
Hepacivirus/genética , Hepatitis C/virología , Diálisis Renal , Genotipo , Hepatitis C/epidemiología , Humanos , Incidencia , Polimorfismo Conformacional Retorcido-Simple , Prevalencia , Venezuela/epidemiologíaRESUMEN
The presence of antibodies against Norwalk virus (NV) was studied in sera from different Venezuelan populations, using an enzyme immuno-assay (EIA) based on recombinant NV protein. Antibodies to NV were found in 47%-53% of urban subjects from Caracas, 83% of rural subjects from the west of the country, and 73%-93% of Amerindian subjects. The prevalences found in the rural and Amerindian groups were significantly higher than that in the urban group. Although about 50% of the children studied were seropositive for NV by the age of 5 years, only four (0.4%) of 1120 faecal samples from children with diarrhoea which were tested for the presence of NV antigen by sandwich EIA were found positive. An increase of at least 4-fold in the titre of anti-NV IgA was found in three (5%) of 61 pairs of sera taken during and 1 month after an acute episode of diarrhoea not due to rotavirus. NV was therefore not a predominant aetiological cause of gastro-enteritis in young children in Venezuela between 1993 and 1995, although it can be the cause of diarrhoea in infants.
Asunto(s)
Infecciones por Caliciviridae/epidemiología , Gastroenteritis/virología , Virus Norwalk/inmunología , Adolescente , Adulto , Anticuerpos Antivirales/análisis , Niño , Preescolar , Heces/virología , Femenino , Humanos , Técnicas para Inmunoenzimas , Indígenas Sudamericanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Virus Norwalk/aislamiento & purificación , Embarazo , Prevalencia , Venezuela/epidemiologíaRESUMEN
Recently, a new virus related to flaviviruses, the hepatitis G virus (HGV), or GBV-C virus, was discovered as a putative blood-borne human pathogen. HGV RNA (NS5 region) was amplified by reverse transcription-nested PCR in the sera of 6 of 64 (9%) hemodialysis patients; 2 of 80 (2.5%) West Yukpa Amerindians, a population with a high rate of HBV infection but negative for HCV infection; and 1 patient with an acute episode of non-A, non-B, non-C hepatitis (NABCH). The patterns of single-strand conformation polymorphism of the amplified products were unique among different specimens and similar on follow-up for hemodialysis patients. All patients tested remained HGV RNA positive 1 and 2 years later, without major sequence variation, except for the NABCH patient, for whom a double infection and an apparent clearance of the original dominant variant was observed after 2 years. The sequences of the NS5 amplified products demonstrated 85 to 90% identity with other reported HGV sequences.
Asunto(s)
Flaviviridae/aislamiento & purificación , Hepatitis Viral Humana/diagnóstico , Hepatitis Viral Humana/epidemiología , ARN Viral/sangre , ARN Viral/aislamiento & purificación , Secuencia de Bases , Clonación Molecular , Flaviviridae/genética , Hepatitis C/diagnóstico , Hepatitis E/diagnóstico , Hepatitis Viral Humana/sangre , Humanos , Indígenas Sudamericanos , Datos de Secuencia Molecular , Filogenia , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Polimorfismo Conformacional Retorcido-Simple , ARN Viral/genética , Diálisis Renal/efectos adversos , Análisis de Secuencia de ARN , Venezuela/epidemiologíaRESUMEN
Hepatitis C virus genotypes in Venezuela were analyzed by restriction fragment length polymorphism in the 5' noncoding region. The absence of BstUI digestion was found to be a useful marker for genotype 2 specimens. From 122 serum samples, 66, 20, and 2.5% were classified as genotypes 1, 2, and 3, respectively; 0.8% were classified as genotype 4; and 10% appeared to be mixed infections.
Asunto(s)
Hepacivirus/genética , Hepatitis C/virología , Genes Virales/genética , Genotipo , Hepacivirus/aislamiento & purificación , Hepatitis C/epidemiología , Humanos , Datos de Secuencia Molecular , Venezuela/epidemiologíaRESUMEN
New techniques to control the potential in membrane patches are giving in detail important characteristics of the pre- and post-synaptic channels. When used to assess the quantal size regulation during synchronous (evoked) or asynchronous (spontaneous) release of neurotransmitter can provide valuable information above this process. The macropatch technique (a version of the original patch clamp technique), has advantages in comparison with other macroscopic voltage clamp techniques to record the miniature end-plate current, mepc. During this focal recording, the puzzle size variation of mepc's amplitudes produced, from events generated over distant parts of the cell, are removed. The quantal response is an important feature during synaptic plasticity. Therefore, in this review we focus on pre- and post-synaptic aspects from the quantal asynchronous release of neurotransmitter, that occurs in the neuromuscular junction. We take emphasis on the caudal muscle of tadpoles from amphibian.